The invention relates to an apparatus for damping torsional vibrations in a motor vehicle drive line comprising a gearbox and transmitting the driving torque of an internal combustion engine.
Known from DE-A-34 04 738 is a friction clutch disposed in the drive line of a motor vehicle between its internal combustion engine and its gearbox and of which the clutch plate comprises a torsion vibration damper. The torsion vibration damper has an input part which carries the clutch friction linings of the clutch plate and which is therefore driven by the internal combustion engine and, rotatable relative to the input part and seated on the input shaft of the gearbox an output part which is coupled in a torsionally resilient manner via a plurality of springs. The torsion vibration damper diminishes irregularities in the transmission of torque in the drive line such as occur particularly during a crankshaft rotation by virtue of successive firings of the internal combustion engine. However, there are often instances where the irregularity of rotation can only be unacceptably compensated by means of the prior art torsion vibration damper. Where the prior art friction coupling is concerned, therefore, an additional mass is provided which is rotatable in relation to the output part of the torsion vibration damper and which can be coupled to the output part of the torsion vibration damper when desired in order to suppress gearbox rattle. The resultant improvement in vibration damping is however likewise insufficient for many applications.
It is known from DE-A 32 30 607 to utilize the dynamo which is driven by the internal combustion engine in order to reduce irregularities in the driving torque. By means of a control circuit which responds to the time-related variation in the angular speed of the crankshaft, the energizing current of the dynamo is so influenced that the load moment which the dynamo opposes to the driving torque of the internal combustion engine seeks to compensate for fluctuations in the driving torque. The rotor of the dynamo in the prior art apparatus is at the same time used as a flywheel for the internal combustion engine. In order to be able to compensate for irregularities in crankshaft rotation, the prior art apparatus requires a comparatively rapid control circuit. The vibration-damping effect is nevertheless inadequate for many applications since the excitation of the dynamo cannot be varied at will if its generator function is not to be adversely affected.
Thus it is an object of the invention to indicate a way whereby torsion vibrations occasioned in the drive line of a motor vehicle due to the non-uniformity of the internal combustion engine can be damped more satisfactorily than hitherto.